Children will also be excluded if they have: (i) history of chronic gastrointestinal disorder; (ii) diarrheal illness in the past 2 weeks (diarrhea defined as passage of 3 or more abnormally loose or watery stool in a 24 hour period; (iii) any febrile illness in the preceding week; (iv) other chronic illness; (v) history of receiving antibiotic treatment within the last 7 day; and (vi) severe protein energy malnutrition (PEM). The nutritional status of the children will be assessed using anthropometric measurements (weight-for-age, and weight-for-length/height); children below -2SD for weight for height/length of the NCHS median will not be enrolled. Similarly, children who have received zinc in the past two months will also not be recruited.